1. Field of the Invention
The present invention relates to an autoanalyzer for analyzing components contained in a liquid and a dispensing method thereof, and more particularly, to an autoanalyzer for automatically measuring components contained in a body fluid by dispensing the body fluid such as human blood or urine and a probe elevating method thereof.
2. Description of the Related Art
An autoanalyzer measures a light transmitting amount to check a variation in a color tone and the like generated during a reaction of a mixed liquid produced by mixing an examined sample dispensed into a reaction container with a reagent corresponding to a measurement item such as biochemistry or immunity, thereby measuring a ferment activation or a density for each examined material in the examined sample.
The autoanalyzer measures a measurement item selected in accordance with an examination among a plurality of measurement items, which can be measured in accordance with an analysis condition setting for each examined sample. Then, the reagent corresponding to the measurement item and the examined sample are dispensed into the reaction container via a sample/reagent dispensing probe, the examined sample and the reagent dispensed into the reaction container are stirred by a stirrer to be mixed, and then the mixed liquid is measured by a photometric portion. Additionally, the sample/reagent dispensing probe contacting with the examined sample and the reagent, the stirrer, and the reaction container contacting with the mixed liquid are cleaned and used again for the next measurement.
In the recent autoanalyzer, respective analysis units are interlocked with each other and are operated at a high speed so that the measurement operation of the examined sample is carried out in a predetermined short analysis cycle and a plurality of measurement items and a plurality of examined samples are processed at a high speed.
Then, in an examined sample dispensing process, for 1 analysis cycle, the sample dispensing probe sucks the examined sample in a sample container via a pressure transmission medium such as water inserted in the sample dispensing probe, a tube between the sample dispensing probes, and a sample dispensing pump for performing a suction/discharge operation, and a sample dispensing arm horizontally moves and elevates the sample dispensing probe so as to discharge the sucked examined sample into the reaction container.
In the suction operation of the first dispensing operation upon performing the examined sample dispensing process a plurality of times, first, the sample dispensing probe moves horizontally to a position above the sample container and air is sucked into the sample dispensing probe.
Subsequently, after the sample dispensing probe moves horizontally to the position above the sample container, air is sucked. Subsequently, the sample dispensing probe moves down to the examined sample in the sample container, and a liquid surface of the examined sample is detected by a detector when the sample dispensing probe enters the examined sample in the sample container. Subsequently, the sample dispensing probe stops at a suction position slightly deeper than the detection position so as to suck the examined sample.
After the sample dispensing probe moves down, the sample dispensing probe sucks a dummy examined sample and a measurement examined sample from the sample container for the first dispensing operation, and discharges only the first measurement examined sample into the reaction container.
In the n-th dispensing operation (n≧2), the sample dispensing probe operates at the same timing as that of the first sample dispensing process. The sample dispensing probe sucks only the measurement examined sample for the n-th dispensing operation, and discharges only the n-th measurement examined sample into the reaction container. After all of the measurement examined sample dispensing processes ends, the air and the dummy examined sample sucked during the first dispensing operation are discharged and the inside and outside portions of the sample dispensing probe are cleaned after the discharge.
An air layer and a dummy examined sample layer are formed inside the sample dispensing probe during the suction operation of the first dispensing operation so as to isolate each measurement examined sample sucked into the sample dispensing probe from the pressure transmission medium and to prevent the measurement examined sample from diluting due to a mix with the dispersed pressure transmission medium and the like, thereby preventing a deterioration in precision upon dispensing the examined sample (for example, see JP-A-2002-162401).
However, in the suction operation of the dispensing operation, since the sample dispensing probe enters the examined sample in the sample container at a high speed, when the number of the dispensing operations of the same examined sample increases, the number of shocks upon stopping at the suction position increases, and the pressure transmission medium mixes with the air layer formed inside the sample dispensing probe to thereby diffuse a part of the air. As a result, a problem arises in that the air layer is thinned, and a problem arises in that the pressure transmission medium is mixed with the dummy examined sample formed during the first dispensing operation to thereby be diluted because of the thinned air layer. Due to such problems, when the number of the dispensing operations of the same examined sample increases, a problem arises in that the precision upon dispensing the examined sample deteriorates.